class A {
	  final double PI=3.1415926;// PI是常量
	  public double getArea(final double r) {
		  //r =r+1;  //非法，不允许对final变量进行更新操作
	     	  return PI*r*r;
	  }
      	  public final void speak() {
		  System.out.println("您好，How's everything here ?");
     	  } 
}
public class Example5_9 {
	   public static void main(String args[]) {
	    	   A a=new A();
	     	   System.out.println("面积："+a.getArea(100));
		   a.speak();     
    	   }
}
